Electrical apparatus



Feb. 24, 1942. LQFGREN 2,274,489

ELECTRICAL APPARATUS Filed Oct. 1, 1940 2 Sheets-Shet 1 INV OR. 32 27 j MATTORNEY;

Feb- 24, 1942. e. E. LOFGREN ELECTRICAL APPARATUS Filed Oct. 1, 1940 2 Sheets-Sheet 2 A ATIGRNEY.

Patented Feb. 24, 1942 ELECTRICAL APPARATUS Gustaf Einar Lofgren, Riverside, Conn, assignor to Electrolux Corporation, Dover, Del., a corporation of Delaware Application October 1, 1940, Serial No. 359,235

Claims.

My invention relates to electrical apparatus and more particularly to household appliances of this nature.

In such devices it is often desirable to provide controls by means of which their operation may be regulated. Thus, if the device includes an electric motor, such as is used in a vacuum cleaner, it is advantageous to be able to operate the motor at different speeds. Likewise, in the case of a heating device, it is advantageous to provide means for regulating the degree of heat. From a purely electrical standpoint, this may be done by providing a multiposition switch in the circuit of the device, which may be adjusted to givethe desired speed ordegree of heating.

However, experience has proved that in the case of, for instance, a vacuum cleaner provided with a two-speed motor having a control switch of this nature, the device is often operated by persons having little or no knowledge of machinery and who fail to note whether the switch is positioned for high or low speed. Such persons are apt to have the switch in the low-speed position without knowing it or without realizing that the switch has two different speed positions, and become dissatisfied with the operation of the device, assuming that it is running at full speed.

This difliculty may be largely overcome if separate electric plug receptacles are provided and so connected to the current-consuming device as to produce different effects when current is supplied through the different receptacles. Thus, in

venting the connection of different plugs to two live receptacles at the same time.

In accordance with my invention, I provide such means in the form of a double-pole, doublethrow switch connected in both sides of the circuits between the motor and the respective re-' ceptacles, together with means for automatically actuating this switch upon the insertion of a plug in one receptacle so as to connect this receptacle to the motor and to disconnect both prongs of the other receptacle from the motor. Moreover, the structure in accordance with my invention prevents the insertion'of a plug into one recepacle whenever a plug is received in the other.

Further objects and advantages of my invention will be apparent from the following description, considered in connection with the accompanying drawings which form a part of this specification, and of which:

Fig. 1 is a view, partially in cross-section, of a vacuum cleaner embodying my invention;

Fig. 2 is a rear view of the vacuum cleaner shown in Fig. 1;

Fig. 3 is a cross-sectional view on an enlarged scale of a portion of the device shown in Fig. 1;

Fig. 4 is a cross-sectional view taken on the line 4-4 of Fig. 5;

Fig. 5 is a cross-sectional view taken on the line 5-5 of Fig. 3;

avacuum cleaner having a two-speed motor, two

different plug receptacles are provided, one plainly labeled with a legend such as high speed and the other with a legend such as low speed, With such an arrangement, even the least mechanically minded person will in most cases observe and notice the two receptacles and their labels and hence will be able to operate the device at th desired speed.

However, if two receptacles are provided, it is essential that there be means for opening the electrical circuit between the motor and the receptacle which is not in use, whenever a plug is connected to the other receptacle. Most receptacles of this nature in present-day use include a pair of contact prongs which, while surrounded by a shield of some sort, nevertheless may be easily touched by the hand and if these prongs were connected to a,live circuit, it is obvious that there would be great danger of shock. Moreover, means should be provided for pre- Fig. 6 is a view of a switch shown in Fig. 4, as seen from the opposite side; and

Fig. '1 is a wiring diagram.

Referring more particularly to Figs. 1 and 2, reference character In designates the casing of a vacuum cleaner which is adapted to be supported on a surface by means of runners Ii. Suitably mounted within the casing III is an electric motor [2 driving a fan I3. A hose II is connected to one end of the casing and to a hollow handle I5 which carries a suction nozzle l6. Disposed within the casing in between the fan l3 and the point of communication of hose N ha dust-separating member ii. The opposite end of the casing is provided with an exhaust opening i8, as more clearly appears in Fig. 2.

As is well known, rotation of the fan I: by means of the motor I! produces a partial vacuum within the casing l0 and air is hence caused to flow through .the nozzle i6, handle l5 and hose i l to within the dust-separating member H. H the nozzle is passed over a dusty surface, dust is entrained with this air and is carried to the dust-separating member, where it is separated from the air, the latter passing through the fan to be discharged through the exhaust i8.

It is often desirable to vary the suction eflect produced at the nozzle l8, and this may be done by varying the speed of the fan l3, the motor l2 being of the two-speed type. The electrical circuit of the motor is shown in the wiring diagram of Fig. 17. As here illustrated, current may b supplied to the motor circuit through either of the terminals 20 and 2| or 22 and 23. A doublepole switch 24 is connected in the circuit of the terminals 20 and 2|, while a similar switch 25 is connected in the circuit of the terminals 22 and 23. These switches are illustrated diagrammatically as being connected together by means of a mechanical connection 28 so arranged that when one switch is closed the other switch is open.

With the switch 24 closed, as shown in Fig. '1, current may flow from the terminal 28 through the switch 24 and conductor 21 and through the entire field coil 28, the armature 29, the conductor 30, switch 3|, and conductor 32 to the conductor 33 which is connected to one pole of each switch. From here, the current flows through the switch 24, to the terminal 2|. Un-

der these conditions the entire field coil is energized and the motor operates at low speed. It will also be noted that, switch 25 being open, terminals 22 and 23 are both disconnected from the live motor circuit and consequently a person could contact these terminals without any danger of receiving a shock. Moreover, should the terminals 22 and 23 be connected to a source of current, this current would not be fed into the motor circuit.

If the switches 24 and 25 are placed in the opposite positions from that shown in Fig. 7, that is, with switch 25 closed and switch 24 open, and current is supplied to the terminals 22 and 23, the current will flow from the terminal 22 through the switch 25 and conductor 34 to an intermediate point of the field coil 28. From here it will continue through the lower portion of the field coil, the armature 29, conductor, 38, switch 3| and conductors 32 and 33 and the other pole of the switch 25 back to the terminal 23. Inasmuch as only a portion of the field coil is energized, the motor will operate at an increased speed. Due to the fact that the switch 24 is open, the terminals 20 and 2| are dead and hence a personcould not obtain a shock from contacting them.

The switch 3| is located in the motor circuit so as to make it possible to start and stop the motor, regardless of the position of the switches 24 and 25.

In Figs. 3 through 6, there is illustrated a practical embodiment in a vacuum cleaner of the circuit shown in Fig. 7. The terminals 20 and 2| are shown as prongs in a plug receptacle 38 located on one side of the vacuum cleaner, while the terminals 22 and 23 are shown as prongs of a receptacle 31 located on the opposite side.

The switches 24 and 25 are combined in a single switch structure, designated generally by reference character 40. This switch includes a chassis 4| made of insulating material and being generally U shaped, the bottom of the U constituting a curved track 42 over which are arranged to run rollers 43 and 44 made of conducting material. These rollers are connected together in axial alignment by insulating material, which is engaged by a member 45 held thereagainst by means of a spring 48. The opposite end of the spring abuts against an apertured disc 41 which loosely surrounds the upper end of member and is formed with a recess having a curved bottom. A member 48 is pivotally mounted at 49 on a bracket 58 which supports the switch and which is secured to a transverse wall 5| in the vacuum cleaner by means of bolts 52. Member 48 includes an arm formed with a curved lower end which engages the curved bottom of the recess in disc 41, whereby the arm and disc may have relative pivotal movement. The above-described parts constitute a snap-action switch, the toggle arrangement holding the contact rollers 43 and 44 at one or the other of the extreme ends of the track 42 and causing them to quickly traverse the track from one end to the other whenever the member 48 is pivoted from one of its extreme positions to the other. The movement of member 48 is limited by a pair of stops 53 and 54 carried by bracket 58.

Mounted on one side of the chassis adjacent to one side of the track 42 are a pair of contacts 58 and 51. Contact 58 is connected to the prong 2| by means of a conductor 58, while conductor 21 is connected to contact 51 and leads to a terminal of the field winding 28 of the motor. Mounted on the opposite side of the chassis adjacent to this same end of the track 42 is a pair of contacts 59 and 80. Contact 59 is connected to prong 20 by means of a conductor 8|, while contact 88 is connected to the switch 3| by means of the conductor 32.

Contact 88 is a part of a member which also includes a contact 82 located on the same side of the switch chassis, but adjacent to the opposite end of the track 42. The material connecting contacts 88 and 82 corresponds to conductor 33 in the wiring diagram shown in Fig. 7. Located adjacent to contact 82 is a contact 83 which is connected by means of a. conductor 84 with the prong 22 of the receptacle 31. The other prong 23 in this receptacle is connected by means of a conductor 85 with a contact 88 located on the same side of the chassis as are contacts 58 and 51, but at the opposite end of the track 42. Adjacent to contact 88 is a contact 81 which is connected by means of conductor 34 with an intermediate point in the field coil 28. The switch 3| is connected to the armature of the motor through the conductor 38 which leads to one of the brushes.

The various pairs of contacts are so located that they may be bridged by either the roller 43 or the roller 44. Thus, with the switch in the position illustrated in Figs. 4 and 6, the roller 43 bridges the contacts 58 and 51, while the roller 44 bridges the contacts 59 and 88. This position of the switch corresponds to that shown in the wiring diagram of Fig. '1 and consequently current is supplied to the entire field coil and the motor operates at low speed. With the switch in the opposite position, the roller 43 would bridge the contacts 88 and 81, while the roller 44 would bridge the contacts 82 and 83 and current would be supplied to only a portion of the field coil, thus causing the motor to operate at an increased speed.

The switch is shifted from one position to the other by means of slidable structure 10 which extends through the bases of receptacles 38 and 31, where it is disposed between the prongs, as is clearly shown in Fig. 5. Structure 18 is made up of a central metallic portion 1| and end DOT;

tions 12 and 13 which are preferably made of insulating material. The central portion 1| is connected to member 48 by means of a loose pivot, which has suflicient play to permit member 48 to move in an arc while member II moves in a straight line. 4

Member is shifted by the insertion of an electric plug into either of the receptacles 36 or 31. As shown in Figs. 4 and 5, plug 15 is inserted in receptacle 36 and member 10 has been moved to the left, as viewed in these figures. This has caused member 48 to pivot in a counterclockwise direction, as viewed in Fig. 4, and this in turn has positioned the rollers 33 and 34 so as to cause roller 43 to bridge contacts 56 and 51 and to cause roller 44 to bridge contacts 59 and 60.

Inasmuch as neither contacts 85 and 61 nor contacts 62 and 63 are bridged, prongs 22 and 23 are disconnected from the motor circuit and consequently could be touched without giving a shock. Moreover, if the prongs 22 and 23 were to be connected to a source of electricity by means of another plug, the current would not be conveyed to the motor circuit. However, due to the fact that portion 13 of the member 10 extends a substantial distance into receptacle 31, it would be impossible to insert a plug in this receptacle unless sufiicient force were applied to dislodge the plug 15 from the receptacle 36.

In the event it is desired to operate the motor at maximum speed, the plug 15 is removed from the receptacle 36 and placed in the receptacle 31. The insertion of the plug in this latter receptacle displaces the member 13 to the right, as viewed in Figs. 4 and 5, and this in turn shifts the switch to a position in which roller 43 bridges contacts 66 and B1 and roller 44 bridges contacts 62 and 63. Thus current is supplied to an intermediate point of the field winding and the motor runs at maximum speed. Due to the fact that neither contacts 66 and 51 nor contacts 59 and 60 are bridged, the prongs and 2| are disconnected from the motor circuit.

There is thus provided an arrangement which reduces to a minimum the possibility of confusion with respect to the speed at which the motor is operating, and which at the same time is absolutely safe and foolproof. While I have shown my invention as being used in connection with a vacuum cleaner, it is obvious that it may be employed with advantage in any electrical device, and the scope of my invention is not to be limited by the embodiment described for purposes of illustration, but is to be determined by the appended claims.

.a circuit connected to each of said members,

and means actuated by the connection of a plug to anyone of said members for opening the circuit to which the remainder of said members is connected.

2. In an electrical device, a plurality of separate and independent plug-receiving members, and means actuated by the connection of a plug to any one of said members for preventing the connection of another plug to the remainder of said members.

3. In an electrical device, a plurality of plugreceiving receptacles, a pair of electric conductors connected to each receptacle, an electric switch in each of said conductors, and means actuated by the connection of a plug to any one of said receptacles for closing the switches in the pair of conductors connected to that receptacle and for opening the remainder of said switches.

4. In an electrical device, a pair of plug-receiving receptacles, a pair of electric conductors connected to each receptacle, an electric switch in each of said conductors, and movable structure having portions disposed in said receptacles and adapted to be moved by the insertion of a plug into either of the receptacles for shifting said switches, so as to close the switches in the conductors connected to the receptacle into which the plug is inserted and to open the other switches.

5. In an electrical device, a pair of oppositely disposed plug-receiving receptacles, a pair of electric conductors connected to each receptacle, switch structure disposed between said receptacles, said structure including an electric switch in each of said conductors having movable contact making and breaking means, and movable structure extendable into either of said receptacles and adapted, by the insertion of a plug into that receptacle in which said movable structure is extending, to be moved so as to extend into the other receptacle, said contact-making and breaking means beingoperatively connected to said movable structure so as to close the switches in the conductor connected to the re ceptacle into which the plug is inserted and to open the other switches.

GUSTAF EINAR LOFGREN. 

